Problem 5.93

In a two-beam interferometer the orange mercury line composed of two wavelengths \(\lambda_{1}=576.97 \mathrm{nm}\) and \(\lambda_{2}=579.03 \mathrm{nm}\) is employed. What is the least order of interference at which the sharpness of the fringe pattern is the worst?

k_{\min }=1 / 2 \lambda_{1} /\left(\lambda_{2}-\lambda_{1}\right)=140

Interference of Light